A video system which provides a stereoscopically perceivable video image typically comprises a display device configured to alternately switch the display between a left video image created so as to be viewed by the left eye and a right video image created so as to be viewed by the right eye; and an eyeglass device, which assists in viewing the video to allow a viewer to stereoscopically perceive the video displayed by the display device. The eyeglass device typically comprises an optical shutter including a left shutter which increases and decreases a transmission light amount to the left eye and a right shutter which increases and decreases a transmission light amount to the right eye. The optical shutter is controlled so as to open and close in synchronism with switching of the video image, so that the viewer views the left video image with the left eye only and the right video image with the right eye only. Therefore the viewer stereoscopically perceives the video displayed by the display device.
An illumination device such as a fluorescent lamp typically blinks at a consistent frequency. According to Patent Document 1, if the aforementioned video system is used in a lighting environment in which the illumination device blinks at a consistent frequency, mismatching between the lighting frequency of the illumination device and the open/close control operation of the optical shutter in the eyeglass device causes flicker. The technologies disclosed in Patent Document 1 uses the blanking time period between frame images of a video displayed by the display device to adjust an open time period of the optical shutter of the eyeglass device.
However, it is still insufficient to suppress the flicker by means of the adjustment of the open time period of the optical shutter according to the technologies disclosed in Patent Document 1.    Patent Document 1: Japanese Patent Application Publication No. H9-138384